화학공학소재연구정보센터
Inorganic Chemistry, Vol.59, No.9, 6432-6438, 2020
Microwave Spectra and Theoretical Calculations for Two Structural Isomers of Methylmanganese Pentacarbonyl
The first microwave rotational spectra for two structural isomers of methylmanganese pentacarbonyl were measured in the 4-9 GHz range using a pulsed-beam Fourier transform microwave spectrometer. The spectra for the two isomers, a symmetric-top structure and an asymmetric-top acyl isomeric structure, were fit to obtain rotational and centrifugal distortion constants and Mn-55 quadrupole coupling parameters. The rotational constants, the manganese (Mn-55) nuclear quadrupole coupling constant, the centrifugal distortion constants, and the spin-rotation constant were determined for the symmetric CH3Mn(CO)(5) and have the following values: A = B = 793.153(3) MHz, D-J = 0.00040(4) MHz, D-JK = 0.0018(2) MHz, C-cc = 0.183(6) MHz, and eQq(cc)= -87.4(3) MHz. Rotational constants and 5s Mn quadruple coupling constants were determined for the isomeric acyl-CH 3 C(O)Mn(CO)(4) and have the following values: A = 839.96(4) MHz, B = 774.20(7) MHz, C = 625.63(1) MHz, and 1.5 eQq(aa )= 44.9(47) MHz and 0.25(eQq(bb) - eQq(cc)) = 11.9(12) MHz. The measured rotational constants from the isomeric acyl-CH3C(O)Mn(CO)(4 )were compared with various theoretical computations. The calculated rotational constants for the dihapto-acyl and the agostic-acyl structures are reasonably close to the experimental values. We note that the calculated dihapto-acyl structure most closely matches the experimental data, as the calculation for the dihapto structure using the B3LYP functional with the aug-cc-pVDZ basis set closely reproduced the experimental values for A, B, and C.